title: Differential expression of epigenetic modulators during human embryonic stem cell differentiation.
abstract: Although the progression of aging and the diseases associated with it are extensively studied, little is known about the initiation of the aging process. Telomerase is down-regulated early in embryonic differentiation, thereby contributing to telomeric attrition and aging. The mechanisms underlying this inhibition remain elusive, but epigenetic studies in differentiating human embryonic stem (hES) cells could give clues about how and when DNA methylation and histone deacetylation work together to contribute to the inactivation of hTERT, the catalytic subunit of telomerase, at the onset of the aging process. We have confirmed the differentiation status of cultured hES colonies with morphological assessment and immunohistochemical stainings for pluripotent stem cells. In hES cells with varying degrees of differentiation, we have shown a stronger association between hES differentiation and expression of the epigenetic regulators DNMT3A and DNMT3B than between genetic modulators of differentiation such as c-MYC. We also propose a new model system for analyses of stem cell regions, which are differentially down-regulating the expression of hTERT and the actions of epigenetic modulators such as the DNMTs and histone methyltransferases.
authors.affiliation: Department of Biology, University of Alabama at Birmingham, 175 Campbell Hall, 1300 University Boulevard, Birmingham, AL 35294-1170, USA.
authors.forename: Sharla M O
authors.initials: SM
authors.lastname: Phipps
authors.forename: William K
authors.initials: WK
authors.lastname: Love
authors.forename: Troy E
authors.initials: TE
authors.lastname: Mott
authors.forename: Lucy G
authors.initials: LG
authors.lastname: Andrews
authors.forename: Trygve O
authors.initials: TO
authors.lastname: Tollefsbol
mesh_terms: D000375:Aging; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics*; D002478:Cells, Cultured; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000378:metabolism*; D044127:Epigenesis, Genetic; D005347:Fibroblasts / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism; D005786:Gene Expression Regulation; D006657:Histones / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008745:Methylation; D051379:Mice; D008858:Microscopy, Phase-Contrast; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D019098:Telomerase / Q000378:metabolism
chemical_list: D015415:Biomarkers; D005353:Fibronectins; D006657:Histones; D016271:Proto-Oncogene Proteins c-myc; D004248:DNA (Cytosine-5-)-Methyltransferases; D019098:Telomerase; D000469:Alkaline Phosphatase